Cronje injured his ankle in the Springboks’ 37-15 victory over the Argentines in their competition opener in Port Elizabeth on Saturday.
Vermaak, 32, has made three previous test appearances, but none since 2013.
The Boks will also travel without flank Oupa Mohoje, who sustained a rib injury on provincial Currie Cup duty with the Free State Cheetahs this weekend, while flyhalf Handre Pollard will also remain in South Africa to continue his rehabilitation from an ankle injury.
The Boks will travel to Salta via Sao Paulo and Buenos Aires on Wednesday.
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(Reporting By Nick Said; Editing by Clare Fallon)
